content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.joins;
  
  import java.util.Map;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.functions.Consumer;
  
  /**
   * Represents an execution plan for join patterns.
   * @param <R> the result type
   */
  public abstract class Plan<R> {
      abstract ActivePlan0 activate(Map<Object, JoinObserver> externalSubscriptions,
              Observer<R> observer, Consumer<ActivePlan0> deactivate);
  
      @SuppressWarnings("unchecked")
      static final <T> JoinObserver1<T> createObserver(
              Map<Object, JoinObserver> externalSubscriptions,
              Observable<T> observable,
              Consumer<Throwable> onError
              ) {
          JoinObserver1<T> observer;
          JoinObserver nonGeneric = externalSubscriptions.get(observable);
          if (nonGeneric == null) {
              observer = new JoinObserver1<>(observable, onError);
              externalSubscriptions.put(observable, observer);
          } else {
              observer = (JoinObserver1<T>) nonGeneric;
          }
          return observer;
      }
  
      /**
       * Extracts a method reference to the Observer's {@link Observer#onError(java.lang.Throwable) onError}
       * method in the form of an {@link Consumer}.
       * <p>Java 8: observer::onError</p>
       *
       * @param <T> the value type
       * @param observer
       *            the {@link Observer} to use
       * @return an action which calls observer's {@code onError} method.
       */
      protected static <T> Consumer<Throwable> onErrorFrom(final Observer<T> observer) {
          return new Consumer<Throwable>() {
              @Override
              public void accept(Throwable t1) {
                  observer.onError(t1);
              }
          };
      }
  
  }
  